“Basal-like” carcinoma of breast can be identified as:
**Core Concept**
Basal-like breast carcinoma is a subtype of triple-negative breast cancer characterized by the absence of estrogen receptors, progesterone receptors, and excess HER2 protein. These tumors express basal cytokeratins and have a poor prognosis due to their aggressive nature and resistance to endocrine therapy.
**Why the Correct Answer is Right**
Basal-like carcinomas are identified by the expression of basal cytokeratins (e.g., CK5/6, CK14, and CK17) and the absence of estrogen receptors (ER), progesterone receptors (PR), and excess HER2 protein. This subtype accounts for approximately 10-20% of all breast cancers and is more common in younger women and those with a family history of breast cancer.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because basal-like carcinomas are not identified by the presence of HER2 protein; rather, they are characterized by its absence.
**Option B:** This option is incorrect because basal-like carcinomas are not identified by the presence of BRCA1 mutations; while BRCA1 mutations are associated with an increased risk of breast cancer, not all basal-like carcinomas are associated with BRCA1 mutations.
**Option C:** This option is incorrect because basal-like carcinomas are not identified by the presence of lobular carcinoma in situ (LCIS); while LCIS is a risk factor for invasive breast cancer, it is not a characteristic of basal-like carcinomas.
**Clinical Pearl / High-Yield Fact**
Basal-like carcinomas are often aggressive and have a poor prognosis, emphasizing the need for early detection and treatment. These tumors can be challenging to manage due to their resistance to endocrine therapy, highlighting the importance of targeted therapies and clinical trials.
**Correct Answer:** D.